Validation by the stylesheet
A document was previously authored outside of Serna.
A reference was edited through the Attributes dialog when validation mode wasn't Strict.
If there is an inaccessible path, the broken reference is shown in red.
Figure 1. Invalid path is validated by the stylesheet.
Validation by the Schema
When you try to insert an invalid local reference
Strict Validation
The error message appears and the operation is cancelled.
Figure 2. Message: Operation not valid in context.
Validation On
The invalid reference is inserted but a message reporting the not found target appears. You should correct the reference.
Validation Off
The invalid reference is inserted without any messages.
When you open a document with invalid local references
A document was previously authored outside of Serna.
A reference was edited through the Attributes dialog when validation mode wasn't Strict.
If there is an inaccessible path to a target within the current document, validation mode switches from Strict to On, and, in addition to the broken local reference in red, a message reporting the not found target appears.
Figure 4. Serna reports an invalid local reference.